1. Field of the Invention
The present invention relates to an image capturing device and an automatic backlash correction method thereof, and more particularly to the image capturing device and the automatic backlash correction method capable of automatically correcting a backlash compensation value, and correcting the backlash compensation value of a group of zoom lenses after each time of using the image capturing device.
2. Description of the Related Art
In recent years, science and technology advance, the way of recording our life is changed accordingly. In particular, electronic devices with an image capturing function such as camera and video camera have become one of the indispensable daily accessories in outdoor activity. It is noteworthy to point out that the zooming function of a camera can adjust the range of viewing angles of the camera according to user requirements, and assist the user to overcome the environmental factors to obtain a desired screen shot of picture composition when the user is situated at the same photographing location.
In general, the camera can adjust the movement of the group of zoom lenses by using a stepper motor or DC motor to control the rotation of gears, so as to change the focal length to project the light of a remote imaging object into the camera. However, with increasing the time of using the camera, the backlash value of the gears may be changed and thus cause the group of zoom lenses unable to move to a predetermined position accurately and the image quality may be affected.
At present, manufacturers generally count a certain quantity of lenses to obtain an average backlash value and write the calculated average backlash compensation value into a memory as reference for the movement of the group of zoom lenses before cameras are in mass production. Although this method is applicable for most lenses, but not for all lenses. With increasing the time of using the camera, the deviation of backlash value of the group of zoom lenses is not clear after the camera has been manufactured and shipped out from the factory.
In another common technical means adopted in the camera manufacture procedure, each lens is loaded with a firmware of a beta version and added with a process of testing the backlash value of a lens. A backlash compensation value is calculated by the firmware of the beta version and then written into a memory. Before the camera is shipped out from the factory, the firmware of the beta version is updated to a firmware of a released version. Although this method can provide a factory setting of the backlash compensation value to fit all lenses, the manufacturing cost and time are increased. However, with increasing the time of using the camera, the deviation of backlash value of the group of zoom lenses is still not clear after the camera has been manufactured and shipped out from the factory. Therefore, an improved backlash value correction method for cameras is required.
In summary, image capturing device and the automatic backlash correction method in accordance with the present invention can automatically correct the backlash value of the group of zoom lenses for each time when the camera enters into a shutdown procedure in order to drive the group of zoom lenses to move to the originally predetermined position accurately.